Credit to YouTube user BLACK-TRICK for archiving and uploading this in May 2017, along with the fans in the comment section to chime in on this. I'm having a hard time finding more information on this at the moment, but here's what my takeaway is going off some very poor Google translations (since I'm still learning Japanese and it's pitiful at best).
This was recorded in early-mid 1987 at The Loft and La Mama when they were still signed to indie company Taiyou Records and Invitation before catching the attention of Victor shortly there after. As to more information on the number of cassette tapes that were made, I have no idea, but fans said they got them either at shows or pirated shops around the country. So, for the life of me I wouldn't be able to say how rare and sought after this is since there's no listings on discogs or eBay and fansites like This Is Not Greatest Site and Buck-Tick Zone don't even mention them. When it comes to why these songs haven't gotten an official release, not even on This is Not Greatest Hits or any other compilation album, I'm a bit stumped - as fans stated that Boy's Error is one of their favorite tracks. One user, unless the translation I got was just straight up wrong, says that when Imai Hisashi wrote the songs, they were all in the image and style of their original front man Araki before he was let go. So, when Atsushi Sakurai took over after leaving his position as their drummer, things didn't feel right and they became too embarrassed to perform them live.
Of the five tracks, Vacuum Dream is the only one to stand the test of time and would appear on some releases of their album Hurry Up Mode. The names of the unknown tracks aren't clear (unless fans still have their tapes and it says anything) and it's unlikely Boy's Error or Vacuum Dream will ever resurface on their future albums.